Presentation on theme: "Lesson 6.1 Objectives How scientists use fossils to learn about the history of life How organisms evolved more complex forms over time About mass."— Presentation transcript:
Lesson 6.1 Objectives How scientists use fossils to learn about the history of life How organisms evolved more complex forms over time About mass extinctions
Fossil Record – information provided by fossil records and their location. Fossil record lets scientists identify periods during which different species existed.
Cyanobacteria – earliest known organisms in the fossil record ◦ Contained chlorophyll and used photosynthesis to make sugars from carbon dioxide ◦ The bacteria produced oxygen as a by-product of photosynthesis
The first eukaryotes were single-celled The oldest eukaryotes are from algae that lived 2 billion years ago. 600 mya the first multicellular animals (jelly-fish like) evolved.
Bacteria and algae – first life forms on land Primitive insects – first land-dwelling animals
The loss of all the members of a species Mass extinctions – several periods of huge numbers of species have become extinct in a very short time Permian extinction – the largest mass extinction in Earth’s history. Cretaceous Extinction – dinosaurs extinction
Population – is a group of similar species In nature, organisms reproduce a lot but not many can survive.
Variation or differences among individuals Genetic variation happens when offspring get a mix of chromosomes from both parents
An inherited trait that gives an organism’s an advantage in its particular environment
Individuals that adapted in their environment have a good chance of survival. The adaptive trait will be passed on to their offspring. Overtime, the useful trait will become more common in the population
The evolution of a new species from an existing species. Isolation is the key factor that leads to speciation
Lesson 6.3 Objectives How populations increase and decrease in size What factors affect population size and survival How species can become extinct
All populations have the ability to grow rapidly over time Populations tend to remain about the same size
Emigration – the movement of individuals out of the population Limiting factors: RESOURCES COMPETITION PREDATORS DISEASE CATASTROPHIC EVENTS
Lesson 6.4 Objectives How scientists develop theories About the evidence Darwin used to support the theory of natural selection About additional evidence most scientists use today
Theory – is an explanation of natural phenomena based on a wide range of scientific evidence Ancestor – is an early form of an organism from which later forms descend Vestigial Organs – are structures that were fully developed in ancestral organisms but are reduced and unused in later species
Fossils provided evidence that species in the past were very similar to species living in Darwin’s time
Vestigial Organs - similar structures with different functions